Got into a discussion today about Bettas and why they can't co-exist with most other fish without a lot of space.

One opinion was Bettas are naturally territorial, higher than most other fish and therefore need the space. In addition, domestic Betta Splendens are different from their wild cousins and have the aggression ten-fold in them.

The other opinion is that Bettas are not inherently aggressive, but it is a state of mind that they get into as individual fish. People make them out to be more aggressive than they really are. This applies to both wild and domestic Bettas.

I think they are more aggressive in an aquarium setting because its a smaller space, of course, than in the wild. In the wild, a male might cross into another male's territory and they will chase and nip at each other until one is driven off. In an aquarium, one can't run ther other one off because there is no place to go so they will continue fighting to the death.

I think they are more aggressive in an aquarium setting because its a smaller space, of course, than in the wild. In the wild, a male might cross into another male's territory and they will chase and nip at each other until one is driven off. In an aquarium, one can't run ther other one off because there is no place to go so they will continue fighting to the death.

I would think that pretty much nails it. When you have nowhere to retreat to and you feel your space is being invaded, what choice do you have but to defend it?

Plus Betta Splendens were bred to be even more aggressive when fish fighting was popular (it still is in some parts of the world). Selective breeding has made them even more aggressive and territorial. The IBC even judges bettas by how aggressive they are.. its viewed as a good thing.

The tank is just an added factor. A betta in a 150 gal shallow tank would probably be less territorial.

I bet if someone really tried they could breed the aggressiveness out of bettas, like they have with other animals. I think that would be awesome :P I agree with what's been said already: selective breeding to make them more aggressive, along with limited space and how they already were naturally. It's just how they are.

You definitely could. Mellower bettas is something I would love to have in my lines when I start breeding. Not because I think they should be mellow but so many people insist on doing community tanks with them that being less agressive would give the fish a better qual of life. They wouldn't be as stressed out.